func_periodic_hook.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Russell Bryant
 *
 * Russell Bryant <russell@russellbryant.net>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 *
 * \brief Periodic dialplan hooks.
 *
 * \author Russell Bryant <russell@russellbryant.net>
 *
 * \ingroup functions
 */
 
/*** MODULEINFO
    <depend>app_chanspy</depend>
    <depend>func_cut</depend>
    <depend>func_groupcount</depend>
    <depend>func_uri</depend>
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/audiohook.h"
#include "asterisk/test.h"
#define AST_API_MODULE
#include "asterisk/beep.h"
 
/*** DOCUMENTATION
    <function name="PERIODIC_HOOK" language="en_US">
        <synopsis>
            Execute a periodic dialplan hook into the audio of a call.
        </synopsis>
        <syntax>
            <parameter name="context" required="true">
                <para>(On Read Only) Context for the hook extension.</para>
            </parameter>
            <parameter name="extension" required="true">
                <para>(On Read Only) The hook extension.</para>
            </parameter>
            <parameter name="interval" required="true">
                <para>(On Read Only) Number of seconds in between hook runs.
                Whole seconds only.</para>
            </parameter>
            <parameter name="hook_id" required="true">
                <para>(On Write Only) The hook ID.</para>
            </parameter>
        </syntax>
        <description>
            <para>For example, you could use this function to enable playing
            a periodic <literal>beep</literal> sound in a call.</para>
            <para/>
            <example title="To turn on">
            same => n,Set(BEEPID=${PERIODIC_HOOK(hooks,beep,180)})
            </example>
            <example title="To turn off">
            same => n,Set(PERIODIC_HOOK(${BEEPID})=off)
            </example>
            <example title="To turn back on again later">
            same => n,Set(PERIODIC_HOOK(${BEEPID})=on)
            </example>
            <para>It is important to note that the hook does not actually
            run on the channel itself.  It runs asynchronously on a new channel.
            Any audio generated by the hook gets injected into the call for
            the channel PERIODIC_HOOK() was set on.</para>
            <para/>
            <para>The hook dialplan will have two variables available.
            <variable>HOOK_CHANNEL</variable> is the channel the hook is
            enabled on.  <variable>HOOK_ID</variable> is the hook ID for
            enabling or disabling the hook.</para>
        </description>
    </function>
 ***/
 
static const char context_name[] = "__func_periodic_hook_context__";
static const char exten_name[] = "hook";
static const char full_exten_name[] = "hook@__func_periodic_hook_context__";
 
static const char beep_exten[] = "beep";
 
/*!
 * \brief Last used hook ID
 *
 * This is incremented each time a hook is created to give each hook a unique
 * ID.
 */
static unsigned int global_hook_id;
 
/*! State put in a datastore to track the state of the hook */
struct hook_state {
    /*!
     * \brief audiohook used as a callback into this module
     *
     * \note The code assumes this is the first element in the struct
     */
    struct ast_audiohook audiohook;
    /*! Seconds between each hook run */
    unsigned int interval;
    /*! The last time the hook ran */
    struct timeval last_hook;
    /*! Dialplan context for the hook */
    char *context;
    /*! Dialplan extension for the hook */
    char *exten;
    /*! Hook ID */
    unsigned int hook_id;
    /*! Non-zero if the hook is currently disabled */
    unsigned char disabled;
};
 
static void hook_datastore_destroy_callback(void *data)
{
    struct hook_state *state = data;
 
    ast_audiohook_lock(&state->audiohook);
    ast_audiohook_detach(&state->audiohook);
    ast_audiohook_unlock(&state->audiohook);
    ast_audiohook_destroy(&state->audiohook);
 
    ast_free(state->context);
    ast_free(state->exten);
    ast_free(state);
}
 
static const struct ast_datastore_info hook_datastore = {
    .type = AST_MODULE,
    .destroy = hook_datastore_destroy_callback,
};
 
/*! Arguments to the thread that launches the hook */
struct hook_thread_arg {
    /*! Hook ID */
    char *hook_id;
    /*! Name of the channel the hook was set on */
    char *chan_name;
    /*! Dialplan context for the hook */
    char *context;
    /*! Dialplan extension for the hook */
    char *exten;
};
 
static void hook_thread_arg_destroy(struct hook_thread_arg *arg)
{
    ast_free(arg->hook_id);
    ast_free(arg->chan_name);
    ast_free(arg->context);
    ast_free(arg->exten);
    ast_free(arg);
}
 
static void *hook_launch_thread(void *data)
{
    struct hook_thread_arg *arg = data;
    struct ast_variable hook_id = {
        .name = "HOOK_ID",
        .value = arg->hook_id,
    };
    struct ast_variable chan_name_var = {
        .name = "HOOK_CHANNEL",
        .value = arg->chan_name,
        .next = &hook_id,
    };
 
    ast_pbx_outgoing_exten("Local", NULL, full_exten_name, 60,
            arg->context, arg->exten, 1, NULL, AST_OUTGOING_NO_WAIT,
            NULL, NULL, &chan_name_var, NULL, NULL, 1, NULL);
 
    hook_thread_arg_destroy(arg);
 
    return NULL;
}
 
static struct hook_thread_arg *hook_thread_arg_alloc(struct ast_channel *chan,
        struct hook_state *state)
{
    struct hook_thread_arg *arg;
 
    if (!(arg = ast_calloc(1, sizeof(*arg)))) {
        return NULL;
    }
 
    ast_channel_lock(chan);
    arg->chan_name = ast_strdup(ast_channel_name(chan));
    ast_channel_unlock(chan);
    if (!arg->chan_name) {
        hook_thread_arg_destroy(arg);
        return NULL;
    }
 
    if (ast_asprintf(&arg->hook_id, "%u", state->hook_id) == -1) {
        hook_thread_arg_destroy(arg);
        return NULL;
    }
 
    if (!(arg->context = ast_strdup(state->context))) {
        hook_thread_arg_destroy(arg);
        return NULL;
    }
 
    if (!(arg->exten = ast_strdup(state->exten))) {
        hook_thread_arg_destroy(arg);
        return NULL;
    }
 
    return arg;
}
 
static int do_hook(struct ast_channel *chan, struct hook_state *state)
{
    pthread_t t;
    struct hook_thread_arg *arg;
    int res;
 
    if (!(arg = hook_thread_arg_alloc(chan, state))) {
        return -1;
    }
 
    /*
     * We don't want to block normal frame processing *at all* while we kick
     * this off, so do it in a new thread.
     */
    res = ast_pthread_create_detached_background(&t, NULL, hook_launch_thread, arg);
    if (res != 0) {
        hook_thread_arg_destroy(arg);
    }
 
    return res;
}
 
static int hook_callback(struct ast_audiohook *audiohook, struct ast_channel *chan,
        struct ast_frame *frame, enum ast_audiohook_direction direction)
{
    struct hook_state *state = (struct hook_state *) audiohook; /* trust me. */
    struct timeval now;
    int res = 0;
 
    if (audiohook->status == AST_AUDIOHOOK_STATUS_DONE || state->disabled) {
        return 0;
    }
 
    now = ast_tvnow();
    if (ast_tvdiff_ms(now, state->last_hook) > state->interval * 1000) {
        if ((res = do_hook(chan, state))) {
            const char *name;
            ast_channel_lock(chan);
            name = ast_strdupa(ast_channel_name(chan));
            ast_channel_unlock(chan);
            ast_log(LOG_WARNING, "Failed to run hook on '%s'\n", name);
        }
        state->last_hook = now;
    }
 
    return res;
}
 
static struct hook_state *hook_state_alloc(const char *context, const char *exten,
        unsigned int interval, unsigned int hook_id)
{
    struct hook_state *state;
 
    if (!(state = ast_calloc(1, sizeof(*state)))) {
        return NULL;
    }
 
    state->context = ast_strdup(context);
    state->exten = ast_strdup(exten);
    state->interval = interval;
    state->hook_id = hook_id;
 
    ast_audiohook_init(&state->audiohook, AST_AUDIOHOOK_TYPE_MANIPULATE,
            AST_MODULE, AST_AUDIOHOOK_MANIPULATE_ALL_RATES);
    state->audiohook.manipulate_callback = hook_callback;
 
    return state;
}
 
static int init_hook(struct ast_channel *chan, const char *context, const char *exten,
        unsigned int interval, unsigned int hook_id)
{
    struct hook_state *state;
    struct ast_datastore *datastore;
    char uid[32];
 
    snprintf(uid, sizeof(uid), "%u", hook_id);
 
    if (!(datastore = ast_datastore_alloc(&hook_datastore, uid))) {
        return -1;
    }
 
    if (!(state = hook_state_alloc(context, exten, interval, hook_id))) {
        ast_datastore_free(datastore);
        return -1;
    }
    datastore->data = state;
 
    ast_channel_lock(chan);
    ast_channel_datastore_add(chan, datastore);
    ast_audiohook_attach(chan, &state->audiohook);
    ast_channel_unlock(chan);
 
    return 0;
}
 
static int hook_on(struct ast_channel *chan, const char *data, unsigned int hook_id)
{
    char *parse = ast_strdupa(S_OR(data, ""));
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(context);
        AST_APP_ARG(exten);
        AST_APP_ARG(interval);
    );
    unsigned int interval;
 
    AST_STANDARD_APP_ARGS(args, parse);
 
    if (ast_strlen_zero(args.interval) ||
            sscanf(args.interval, "%30u", &interval) != 1 || interval == 0) {
        ast_log(LOG_WARNING, "Invalid hook interval: '%s'\n", S_OR(args.interval, ""));
        return -1;
    }
 
    if (ast_strlen_zero(args.context) || ast_strlen_zero(args.exten)) {
        ast_log(LOG_WARNING, "A context and extension are required for PERIODIC_HOOK().\n");
        return -1;
    }
 
    ast_debug(1, "hook to %s@%s enabled on %s with interval of %u seconds\n",
            args.exten, args.context, ast_channel_name(chan), interval);
    ast_test_suite_event_notify("PERIODIC_HOOK_ENABLED", "Exten: %s\r\nChannel: %s\r\nInterval: %u\r\n",
            args.exten, ast_channel_name(chan), interval);
 
    return init_hook(chan, args.context, args.exten, interval, hook_id);
}
 
static int hook_off(struct ast_channel *chan, const char *hook_id)
{
    struct ast_datastore *datastore;
    struct hook_state *state;
 
    if (ast_strlen_zero(hook_id)) {
        return -1;
    }
 
    ast_channel_lock(chan);
 
    if (!(datastore = ast_channel_datastore_find(chan, &hook_datastore, hook_id))) {
        ast_log(LOG_WARNING, "Hook with ID '%s' not found on channel '%s'\n", hook_id,
                ast_channel_name(chan));
        ast_channel_unlock(chan);
        return -1;
    }
 
    state = datastore->data;
    state->disabled = 1;
 
    ast_channel_unlock(chan);
 
    return 0;
}
 
static int hook_read(struct ast_channel *chan, const char *cmd, char *data,
           char *buf, size_t len)
{
    unsigned int hook_id;
 
    if (!chan) {
        return -1;
    }
 
    hook_id = (unsigned int) ast_atomic_fetchadd_int((int *) &global_hook_id, 1);
 
    snprintf(buf, len, "%u", hook_id);
 
    return hook_on(chan, data, hook_id);
}
 
static int hook_re_enable(struct ast_channel *chan, const char *uid)
{
    struct ast_datastore *datastore;
    struct hook_state *state;
 
    if (ast_strlen_zero(uid)) {
        return -1;
    }
 
    ast_channel_lock(chan);
 
    if (!(datastore = ast_channel_datastore_find(chan, &hook_datastore, uid))) {
        ast_log(LOG_WARNING, "Hook with ID '%s' not found on '%s'\n",
                uid, ast_channel_name(chan));
        ast_channel_unlock(chan);
        return -1;
    }
 
    state = datastore->data;
    state->disabled = 0;
 
    ast_channel_unlock(chan);
 
    return 0;
}
 
static int hook_write(struct ast_channel *chan, const char *cmd, char *data,
        const char *value)
{
    int res;
 
    if (!chan) {
        return -1;
    }
 
    if (ast_false(value)) {
        res = hook_off(chan, data);
    } else if (ast_true(value)) {
        res = hook_re_enable(chan, data);
    } else {
        ast_log(LOG_WARNING, "Invalid value for PERIODIC_HOOK function: '%s'\n", value);
        res = -1;
    }
 
    return res;
}
 
static struct ast_custom_function hook_function = {
    .name = "PERIODIC_HOOK",
    .read = hook_read,
    .write = hook_write,
};
 
static int unload_module(void)
{
    ast_context_destroy(NULL, AST_MODULE);
 
    ast_custom_function_unregister(&hook_function);
    return 0;
}
 
static int load_module(void)
{
    int res;
 
    if (!ast_context_find_or_create(NULL, NULL, context_name, AST_MODULE)) {
        ast_log(LOG_ERROR, "Failed to create %s dialplan context.\n", context_name);
        return AST_MODULE_LOAD_DECLINE;
    }
 
    /*
     * Based on a handy recipe from the Asterisk Cookbook.
     */
    res = ast_add_extension(context_name, 1, exten_name, 1, "", "",
            "Set", "EncodedChannel=${HOOK_CHANNEL}",
            NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, exten_name, 2, "", "",
            "Set", "GROUP_NAME=${EncodedChannel}${HOOK_ID}",
            NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, exten_name, 3, "", "",
            "Set", "GROUP(periodic-hook)=${GROUP_NAME}",
            NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, exten_name, 4, "", "", "ExecIf",
            "$[${GROUP_COUNT(${GROUP_NAME}@periodic-hook)} > 1]?Hangup()",
            NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, exten_name, 5, "", "",
            "Set", "ChannelToSpy=${URIDECODE(${EncodedChannel})}",
            NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, exten_name, 6, "", "",
            "ChanSpy", "${ChannelToSpy},qEB", NULL, AST_MODULE);
 
    res |= ast_add_extension(context_name, 1, beep_exten, 1, "", "",
            "Answer", "", NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, beep_exten, 2, "", "",
            "Playback", "beep", NULL, AST_MODULE);
    res |= ast_add_extension(context_name, 1, beep_exten, 3, "", "",
            "Hangup", "", NULL, AST_MODULE);
 
    res |= ast_custom_function_register_escalating(&hook_function, AST_CFE_BOTH);
 
    if (res) {
        unload_module();
        return AST_MODULE_LOAD_DECLINE;
    }
    return AST_MODULE_LOAD_SUCCESS;
}
 
int AST_OPTIONAL_API_NAME(ast_beep_start)(struct ast_channel *chan,
        unsigned int interval, char *beep_id, size_t len)
{
    char args[AST_MAX_EXTENSION + AST_MAX_CONTEXT + 32];
 
    snprintf(args, sizeof(args), "%s,%s,%u",
            context_name, beep_exten, interval);
 
    if (hook_read(chan, NULL, args, beep_id, len)) {
        ast_log(LOG_WARNING, "Failed to enable periodic beep.\n");
        return -1;
    }
 
    return 0;
}
 
int AST_OPTIONAL_API_NAME(ast_beep_stop)(struct ast_channel *chan, const char *beep_id)
{
    return hook_write(chan, NULL, (char *) beep_id, "off");
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "Periodic dialplan hooks.",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .requires = "app_chanspy,func_cut,func_groupcount,func_uri",
);